Non-contact infrared fiber-optic device for measuring temperature in a vessel

ABSTRACT

An endoscopic system may include an endoscopic device and a control apparatus. The device may include a housing membrane having a distal end and a transparent outer layer around a periphery of the housing membrane and extending longitudinally from the distal end to define a side volume of interest, and an optical infrared sensor array comprising infrared sensors extending longitudinally along and circumferentially about a longitudinal axis of the device to detect infrared radiation over the side volume. The control apparatus may include a processor and a computer-readable medium having computer-executable instructions that cause the processor to, determine temperature data for the side volume in response to infrared data from the infrared sensor array, determine if the temperature data is in a temperature region of concern in a vessel, and provide a temperature control signal to a subsystem to instruct the subsystem to reduce temperature in the vessel.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. patent application Ser. No. 12/934,008,entitled “Non-Contact Infrared Fiber-Optic Device for MeasuringTemperature in a Vessel” and filed on Sep. 22, 2010, which is a nationalstage entry of PCT Application No. PCT/US2009/38101, filed on Mar. 24,2009, which claims priority to U.S. Patent Application No. 61/038,959,entitled “Non-Contact Infrared Fiberoptic Device for MonitoringEsophageal Temperature to Prevent Thermal Injury During Radio FrequencyCatheter Ablation or Cryoablation” and filed on Mar. 24, 2008. Thedisclosures of all of the above applications are hereby incorporatedherein by reference in their entireties.

FIELD OF TECHNOLOGY

The invention relates to optical probe devices and, more particularly,to optical probe devices for monitoring temperature in a body vessel.

DESCRIPTION OF RELATED ART

Catheter ablation is an effective method of destroying tissue that leadto cardiac arrhythmias. Radio-frequency (RF) catheter ablation, forexample, is commonly used to treat atrial fibrillation (AF) which is themost common heart arrhythmia leading to hospitalization. A catheter isinserted into a patient's heart or other vessel, and heat is applied toa localized region until the tissue in that region has been sufficientlydestroyed to abate the arrhythmia. In other applications, cryoablationhas also been used to freeze and destroy local tissue

Although thermal RF treatments are useful, it is difficult to determinewith sufficient accuracy the parameters needed for successful RFtreatment. Inexactness in the amount of heat or exposure time of anaffected tissue may lead to thermal injury and coagulative necrosis.Radiofrequency catheter ablation of the heart is particularlysusceptible to such problems, because the lesion depth within atreatment site and the tissue diameter (and thickness) of adjacentesophageal vessel will vary across patients from a few mms to 10-15 mms.As such, the required available amount of RF energy to treat the heartor aortic vessel is difficult to predict. The acceptable temperaturethresholds vary not only based on the treatment vessel but also based onvessels adjacent thereto. This inexactness can be particularlyproblematic in radiofrequency catheter ablation procedures because theesophagus being immediately adjacent the posterior left atrial wallleaves a distance of 5 mm or less between the esophagus and theendocardial surface of the posterior left atrium. If the temperature istoo high given the proximity of the vessels, RF application along theposterior left atrial wall may cause necrosis of the esophageal wall,which may lead to a fistula formation between the atrium (heart) and theesophagus. Such atrioesophageal fistula may lead to infection andsepsis, air and particulate matter emboli to the brain, as well as tostrokes and possible to death, if not diagnosed and treated.

To date there have been no effective measures to prevent atrioesophagealfistula formation. The safest method, in fact, is one that avoids theapplication of RF energy over the entire esophagus. Instead, theesophagus is visualized with a radiopaque material (e.g., Barium)swallowed prior to the procedure. Barium is visible through fluoroscopyduring an X-Ray and thus can be used to visually instruct medicalpersonnel when an ablation catheter is right on the esophagus, so thatthe personnel will know that RF energy is not to be applied and theablation catheter is to be moved elsewhere. There are limitations, ofcourse. For example, critical target sites are often close to theesophagus, such that the failure to ablate these sites will compromisethe efficacy of the procedure. Furthermore, the procedure may not beused for all patients due to the risks of airway protection, forexample, during moderate to deep sedation and anesthesia.

Therefore, the inventor found that it was necessary to monitor fordevelopment of a temperature rise within the esophagus or vessel duringRF ablation in the posterior left atrium, such that when a minimalincrease in temperature is noted in the esophagus then RF ablation canbe terminated and inadvertent esophageal injury can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a distal portion of an fiber-optic assembly portionof an infrared sensor;

FIG. 1B illustrates a proximal portion of the fiber-optic assemblyportion of FIG. 1 and connected to an infrared sensor;

FIG. 2A illustrates an end view of the fiber-optic assembly portion ofFIG. 1A;

FIG. 2B illustrates an end view of an fiber-optic assembly portion inaccordance with another example;

FIG. 3 illustrates an infrared sensor array;

FIG. 4 illustrates the infrared sensor of FIG. 1A deployed in a vesselof a human body;

FIG. 5 illustrates a control system for controlling operation ofinfrared sensing using the sensor of FIG. 1;

FIG. 6 illustrates a block diagram of a technique for infrared sensingas executed by the control system of FIG. 5, in accordance with anexample;

FIG. 7 illustrates an infrared sensor in accordance with anotherexample;

FIG. 8 illustrates an infrared sensor in accordance with yet anotherexample; and

FIG. 9 illustrates an example feedback control of an ablation catheterusing an infrared sensor.

DETAILED DESCRIPTION

Generally speaking, various body sensor apparatuses are described tomonitor temperature changes within a body vessel, such as the esophagus.Many conventional temperature sensors (RTD, thermistors andthermocouples) depend upon direct tissue contact or very close physicalcontact to sense temperature. The present application allows themonitoring of spot or “point” measuring as well as large areas oftemperature monitoring through the use of non-contact temperaturesensors. This is particularly important for hollow vessels like theesophagus where conventional sensors are limited because such sensorscannot physically contact all walls at all times.

The present application also describes techniques that can sensetemperature changes along a length and around a partial or fullcircumference of a body cavity or lumen structure. This ability tomeasure temperature over an area of interest may be particularlybeneficial within the esophagus during RF catheter ablation treatmentsof the left atrium, because the two abut over a length of up to 5-6 cmand over a width of up to 4-5 cm. Therefore, by being able to measurethe thermal radiation or portion of the infrared part of theelectromagnetic spectrum over a small “point” to a large field of field,the margin of safety is greatly improved. Any temperature increase isrecognized within the entire lumen of the esophagus and withoutnecessarily having direct contact with the lumen.

In some examples, fiber-optic temperature sensors are able to sensetemperature, and more particularly temperature changes, based on theamount of thermal electromagnetic radiation received (e.g., infraredradiation detected) from the esophageal wall and directed to ahigh-resolution infrared sensor. In some examples, that sensor may be aninfrared camera able to produce a 2-D and or 3-D temperature image mapof the region of interest. In other examples, as discussed herein, thesensor may be an infrared sensor that determines high/low peaktemperature values, average temperature values, changes in temperatureover time or over a spatial distance, etc. The fiber-optic temperaturesensors are formed of a probe that may be attached to the infraredsensor through a lightproof attachment. The probe can be covered with acoating susceptible to gas sterilization and thus usable multiple timesby medical personnel. Yet, in other examples, the probe can be a limiteduse or single use device.

The probes may have both side-view and end-view capabilities thattogether offer 360° infrared sensing within a vessel. This viewingcapacity may be achieved, for example, by using a probe formed ofmultiple fiber-optic channels each with a wide-angle, side view lens asa light coupler. These fiber-optic channels and side view lenses may beorganized such that a minimum length (e.g., 5 cm) of the vessel will bevisible to the sensor device. In other examples, the instrument may bethat of a swing-prism adjustable scope that uses a rotating lens tomeasure a “point” along the lumen to 360° orbital scan. In any of theseexamples, the probe device may be used to measure infrared radiationwithin the esophagus and just behind the posterior left atrium, where RFenergy is often applied during catheter ablation of atrial fibrillationand other arrhythmias.

The infrared energy collected by the fiber-optic channels forming theprobe may be directed to the infrared sensor by angled mirrors withinthe fiber-optic channels. A computer coupled to receive the infrareddata from the sensors is taken through a calibration process duringwhich baseline infrared measurements are acquired prior to theapplication of radiofrequency energy. Once calibration (or a similartechnique) is finished, infrared measurement may occur. In someexamples, the infrared sensor is controlled to sample the vessel at anadjustable rate from 1 Hz to 1000 Hz. Software executed on the computerstores thresholds for temperature levels, such that if the infraredsensor detects an infrared signal corresponding to a temperature abovethe thresholds, the operating personnel may be notified or the systemmay automatically perform a safety function (i.e., stop ablations,deliver a fluid flush to the inside of the lumen). The computer systemmay allow custom spatiotemporal thresholds that measure and react tochanges in temperature as well. It should be noted that althoughabsolute temperature measurements may be provided, the system primarilydepends on a relative increase in temperature compared to a baselineand/or to adjacent pixels.

Instead of having a bundle of fiber-optic channels that communicate thecollected 360° of infrared data to an external infrared sensor, in someexamples the temperature sensing probe has an infrared sensing apparatusplaced at the distal end of the probe where opto-electric conversionoccurs before signals are electronically transmitted to a dataprocessing unit. One such design includes an array of fiber-opticchannels, lenses and mirrors. Infrared radiation is transmitted to aninfrared sensor array embedded within the distal end of the probe andpositioned perpendicular to the long axis of the probe. Electricalsignals from these sensors are then transmitted through the long axis ofthe probe to a main computer.

Another design includes an array of infrared sensors builtcircumferentially along the distal end of the probe to cover up to 360°and extending along an axial length of the probe. Infrared radiation isrelayed directly to these sensors, with or without the use of wide anglelenses and without the need for internal reflectors. After conversion ofthe infrared radiation, signals are transmitted electronically to a maincomputer.

Any of the endoscopic devices and probes described herein may beimplemented in re-sterilizable or disposable forms, biologically inertfor the applications of use.

Examples are described below in reference to particular applications.However, it will be understood that these examples may be useful in anynumber of medical procedures. Cryoablation, for example, has also beenused to destroy cardiac tissue to eliminate arrhythmogenic foci. Thedevices described herein may be used during cryoablation to monitor fordecreases in temperature to prevent esophageal injury. The devices canalso be used monitoring temperature changes during ablation usingdifferent forms of energy such ultrasound, microwave, laser, orconductive heating through use of a balloon that contains heatedsolution, etc.

The applications may be used in any number of bodily cavities orvessels, such as any part of the gastrointestinal tract includingesophagus, stomach, intestines, colon, rectum, etc, as well asgenitourinary tract such as the bladder, uterus, prostate, etc.

FIGS. 1A and 1B illustrate different portions of an infrared sensordevice in the form of an endoscopic device 100 capable of measuringinfrared radiation in a vessel. The device 100 includes two mainportions, a fiber-optic channel assembly 102 that extends from aproximal end 104 (FIG. 1B) to a distal end 106 of the device 100. Theother main portion is a sensor assembly 108 coupled to the fiber-opticchannel assembly 102 through an attachment apparatus 110 and dispersinglens 112. The assembly 102 collects infrared radiation from a vessel'sregion of interest at the distal end 106 and communicates that infraredradiation to the sensor assembly 108. In the illustrated example, thefiber-optic channel assembly 102 is formed of a bundle of individualfiber-optic channels 114, each adjacent at least two other channels toallow for a continuous or nearly continuous viewing region over thecircumference of the assembly 102.

The attachment apparatus 110 may be integrally formed to fixedly orreleasably attach the fiber-optic channel assembly 102 with thedispersing lens 112. The attachment apparatus 110 may be formed as partof a housing member for the fiber-optic channel assembly 102, forexample. In other examples, the attachment apparatus 110 may be a capfor the fiber-optic channel assembly 102. In either example, theattachment apparatus 110 may be glued, fused, or otherwise attached tothe fiber-optic channel assembly 102. The particular ferrule shape ofthe attachment apparatus 110 will very with the application and desiredattachment to the dispersing lens 112—although, the shape should becompatible with multimode operation and coupling to the lens 112.

FIG. 2A shows the fiber-optic channels 114 surrounding a centerfiber-optic channel 116 that also extends from the distal end 106 to theproximal end 104. The channels 114 are modified optical fibers that maybe formed of typical optical fiber materials, such as silica glass,fluorozirconate, fluoroaluminate, and chalcogenide glasses, orcompositions thereof. Yet other suitable materials exhibiting lowabsorption loss for infrared radiation exist, including optical fiberplastics. For measuring thermal conditions within a body cavity, such asan esophagus, infrared radiation in the near infrared and above regionmay be detected, for example, radiation at approximately 900 nm orabove.

The fiber-optic channel assembly 102 is able to collect infraredradiation around a side view of the device 102 along both an axiallength and the entire circumference of the device 100. In this way andas further discussed below, the fiber-optic channel assembly 102 is ableto detect infrared radiation over a two dimensional cylindrical regionof interest. To achieve this expanded region of interest, each of thefiber-optic channels 114 includes an access window 118 for collectinginfrared radiation from the vessel within which the device 100 has beenplaced.

In the illustrated example, the access windows 118 are wide angledlenses each disposed on the periphery of one of the fiber-optic channels114 to collect infrared radiation along the side view. As shown by thedashed lines of FIG. 2A indicating the field of view, in a preferredexample, wide angled lenses are used as the access windows 118 to allowthe assembly 102 to collect infrared radiation from the entirecircumference around the assembly. In this way, more accurate infraredradiation detection can occur. The access windows 118 are shown asconcave lenses. However in other examples, the lenses may be convexlenses or lens systems, diffractive lenses, or other optical elements.

As shown in FIG. 1A, the wide angle lenses 118 are preferably staggeredboth longitudinally along the axis of the fiber-optic channel assembly102 and circumferentially about the circumference of that assembly 102to collect radiation over a three dimensional area of the side view. Inthis way, the lenses 118 follow a helical or near helical path wrappingaround the circumference of the assembly 102.

By longitudinally staggering the wide angle lenses 118 along an axis,the assembly 102 is able to collect radiation over a length of a bodycavity or lumen instead of merely at just a singular side view region.This allows for more accurate detection of infrared radiation and moreaccurate determination of whether for example a body cavity or lumen isexperiencing excessive heat. The wide angle lenses 118 are staggeredcircumferentially about the device 102 by having one wide angle lensdisposed on each of the fiber-optic channels 114 in a bundleconfiguration. This allows the assembly 102 to sense infrared radiationnot only along a length of a body cavity or lumen but around the entireinner wall of a body cavity or lumen as demonstrated in FIG. 3 discussedbelow.

The center fiber 116 shown in FIG. 2A extends to a distal end of theassembly 102 and has its own end face window assembly 120 in the form ofa wide angle lens. This center channel 116 therefore allows the assembly102 to not only detect infrared radiation along a three dimensional sideview region of interest, but also along an end view as well to alloweven greater infrared detection in the body cavity or lumen. This may beparticularly useful in configurations where the device 100 isendoscopically inserted into a body cavity and the distal end 106 isnear abutting or touching a portion of that structure.

In a preferred example, the wide angle lenses 118 are circumferentiallystaggered about the assembly 102 to collectively provide a 360° sideview of a body cavity or lumen and longitudinally staggered to provide aside view along a longitudinal length of at least 5 cm. The length ofthe longitudinal length may vary, as may the degrees of circumferentialcoverage.

The collected infrared radiation from each of the fiber-optic channels114 is coupled to the sensor apparatus 108 through lens 112. In theexample of FIG. 1B, that lens 112 disperses the collected infraredradiation to cover an infrared sensor 122 which, as illustrated in FIG.3, is formed of an infrared sensor array of individual pixels 124, onlya portion of which are numbered for illustration purposes. The infraredsensor 122 may be formed of any suitable material for use infraredradiation detection. Example materials include indium antimonide,amorphous silicon, mercury zinc telluride, mercury(II) cadmium(II)telluride, lead scandium tantalite, lead zirconate titanate, lead(II)selenide, lead(II) sulfide, germanium, and indium gallium arsenide.

As discussed generally above, the lens 112 may be glued, fused, orotherwise attached to the attachment apparatus 110. The lens 112 mayhave a concave or convex shape, or the lens 112 may be a gradient-indexlens having a varying index of refraction profile across the lenssubstrate. In yet other examples, the lens 112 may have a diffractiveprofile for dispersing the collimated incident light from thefiber-optic channel assembly 102. In yet other examples, the lens 112may be eliminated altogether, allowing the attachment apparatus 110 tocouple directly to the infrared sensor 122. In those examples, thedevice may disperse the collected infrared radiation, if desired, byembedding dispersive lenses within each of the fibers forming thefiber-optic channel assembly 102. For example, each lens in the assembly102 could be disposed with a cap end having an embedded gradient indexlens configuration.

FIG. 2B is similar to FIG. 2A but shows six outer fiber-optic channels(seven channels total) instead of the five outer channels shown in FIG.2A. That is, in general, the number of fiber-optic channels forming thechannel assembly 102 can be varied. As the diameter of each fiber-opticchannel decreases, the number of channels in the assembly increases.Smaller diameter channels will limit the size of the wide-anglecollection lens, which means that each lens will collect less infraredradiation. However, more lenses may be used and each lens can bedesigned to have a smaller angle of acceptance in comparison to a largerlens. In general, this demonstrates that variables such as size of thewide-angle lens, the diameter of the fiber-optic channel, the number offiber-optic channels, and the longitudinal displacement of the lensalong the channels can be adjusted to produce an infrared sensor probeof varying size, sensitivity, and collection region of interest (e.g.,extending in the longitudinal direction).

FIG. 4 illustrates a portion of an esophageal cavity having theendoscopic device 100 positioned therein for detecting infraredradiation around a side view region of interest that extends along alength L and around an entire circumference of an inner wall 202 of theesophagus 200 (all partially shown).

The infrared sensor 122 produces an output that is coupled to a signalprocessor such as a controller 300 as illustrated in FIG. 5. Acontroller may register each pixel 124 on a grid. During an initialphase, a calibration is performed to develop a base line temperature forinfrared reading which is recorded for each of the pixels. For example,the controller 300 may register the baseline pixel readings when theendoscopic device 100 is in a known non-formally affected region of abody cavity or lumen. The controller 300 communicates with the infraredsensor 122 over a continuous cycling or at a sampling frequency that isdesired for the way in which the infrared measurements are to be taken.In a preferred example, that sampling frequency may be between 10 and1000 hertz and would correspond to the loop time associated withdetecting and aggregating the infrared signals detected from each of thepixels 124. This sampling frequency would be dependent upon the size ofthe infrared sensor array, and the number of pixels, as well as on theoperating conditions, such as the operating temperature of the sensorarray. While infrared sensing technologies have been developed fornon-cooled systems, it may be desirable to use cooled infrared sensorsfor their increased sensitivity and preferred range of infraredwavelengths.

FIG. 6 illustrates a technique 600 that may be executed by thecontroller 300 in measuring the infrared radiation over an entire sideview such as the side view 204 shown in FIG. 4. The controller 300 maybe a signal processor in a computer, such as a standalone or networkedpersonal computer or diagnostics machine or terminal. A first block 602performs a pixel registration to identify the number of pixels in asensor array. A second block 604 performs a calibration to determine abaseline for reference measurements, which baseline is produced by block606. A block 608 provides an adjustable sampling frequency and refreshrate that the controller 300 uses to determine the parameters fordetecting infrared radiation (or infrared light beams) from the sensorprobe.

A block 610 determines temperature data based on the sensed infraredlight from the sensor probe. More specifically, block 610 may determinea change in temperature, delta temperature, ΔT, from the base linevalues from block 606. The granularity of this determination may be setby the controller 300 or user. For example, the block 610 may measuretemperature changes from the sensor probe in increments of between 0.1to 1° C.

Block 612 determines if the temperature data from block 610 is in atemperature region of concern, for example if a high temperature valueis above a high temperature threshold for ablation catheterapplications, or if a low temperature value is below a low temperaturethreshold for cryoablation catheter applications. The controller 300 maybe programmed to display alert temperature indicators to an operator ofthe endoscopic device 100 so that as a procedure such as an RF catheterablation is performed, an alarm is announced when the temperature withinthe affected esophagus is approaching a potentially detrimental level.

Block 612 may be programmed to identify temporal alerts or otherconditions for alerts such as when a certain number of consecutivemeasurements from the infrared sensor 122 are above a threshold infraredradiation amount. Or the block 612 may trigger based on an absolute timemeasure, such as when the number of seconds over which a continuousmeasurement of an infrared radiation exceeds a threshold value.

The block 612 may also be programmed to provide spatial alertsindicating high temperatures. For example, the controller 300 maydetermine when any pixel or group of sensor pixels (e.g., pixels 124)has an intensity value above a threshold. Or, the block 612 may beprogrammed to identify when a certain percentage of the overall numberof sensor pixels have an intensity value above a threshold level. Insome examples, the block 612 may be programmed to determine when apercentage of adjacent pixels have a threshold intensity above a certainamount. In yet other examples, the determination of high infraredreadings (and thus high temperatures) may be based on spatial resolutionof a change in intensity of infrared radiation, ΔI, delta-intensity,between different pixels or voxels on the sensor. For example, ifcertain pixels have a ΔI, when compared to other pixel measurements,that is above a threshold change intensity value, then the controller300 may determine that a high temperature condition exists.

In other words, spatial alarm adjustments may be based on a singlepixel, a total number of pixels, a percentage of pixels, or a number ofadjacent pixels to determine when it is likely that some portion of thefield of interest in the side view of a body cavity has a temperatureabove a certain threshold amount or a predefined percentage change intemperature compared to a predefined number or percentage of adjacentpixels.

The block 612 also produces a temperature control signal to a subsystemto instruct that subsystem to reduce the temperature. As discussedherein, one such subsystem may be an external ablation-cryoablationcontroller that receives a temperature control signal from the control300 to ramp down or completely turn off the ablation/cryoablationdevice. In other examples, the block 612 may use the temperature controlsignal, indicating an undesired temperature condition in a vessel, tocontrol a cooling catheter disposed within the vessel and designed tocool down a region of interest experiencing threshold high temperatures.Similarly, the block 612 may use the temperature control signal tocontrol a heating catheter disposed within the vessel and designed toheat up a region of interest experiencing threshold low temperatures.

At block 614 the controller 300 is programmed to map the infraredradiation and display changes in the infrared radiation as detected overthe cycle time thereby allowing an operator to visually assess therecorded information as well as being provided a separate alarm inresponse to the programming of block 612.

FIG. 7 illustrates another example endoscopic device 700 similar to thedevice 100 and including a series of fiber-optic channels 702 (only someshown) that are part of an overall fiber-optic channel assembly 704.Each of the channels 702 includes an access window, in this case, a wideangle lens 706, that correspondingly stagger longitudinally andcircumferentially about the assembly 704, as discussed above. Each ofthe fiber-optic channels 702 also includes a mirror 708 that is pairedwith the wide angle lenses 706 to couple light for infrared radiationfrom a distal end of the device 700 to a proximal end. In theillustrated configuration, that coupling is coupled directly into aninfrared sensor 710 that is internal to the device 700. That is, thedevice 700 does not need a separate coupling or attachment apparatus orexternal sensor but rather has a housing body 712 that includes both thesensor and the fiber-optic channel assembly 704.

The infrared signals from the sensor 710 may be coupled to a controllerthrough a wire assembly 714. The outer housing 712 may be a flexiblemembrane, thereby allowing the device 700 to be easily inserted into avessel, while at the same time maintaining sufficient mechanicalintegrity to allow an infrared sensor to be placed directly within thedevice.

In the configuration of FIG. 7, each of the fiber channels, as well asany fiber channels not shown would be positioned to couple theirrespective output signals to a different portion of the infrared sensor710 such that the infrared sensor may be used to resolve the final imageof the entire side view of a body cavity or lumen. This coupling may befor the purposes of measuring infrared radiation. However, it would beunderstood by persons of ordinary skill in the art while reading thisdisclosure that the infrared sensing described herein may also be usedfor temperature sensing across the entire side view of the device aswell. In this case, the system may be designed to measure an aggregatetemperature value over the entire side view or the controller may beprogrammed to determine an overall average temperature value, a peaktemperature value, a change in temperature value, etc., any of which maybe used to identify a high temperature alarm condition depending on theparticular application.

FIG. 8 illustrates another example configuration of an endoscopic device800 that is able to detect infrared radiation over an entire side viewor area of interest within a body cavity or lumen. However, the devicedoes not rely on individual fiber-optic channels bundled together. Nordoes the device rely on staggered access windows or wide angle lenses.But rather the device 800 includes a cylindrical infrared sensor array802 having a plurality of pixels 804 that are configured in acylindrical shape extending along a longitudinal axis of the device 800.Each of the pixels 804 may be a micro infrared sensor individuallycapable of detecting infrared radiation over a portion of a side view ofinterest.

By configuring the pixels in an array configuration around the cylinderof the sensor 802, an entire three dimensional volume may be measured.Each individual sensor 804 couples its detected infrared signal into awire assembly 806 connected to a controller for infrared dataprocessing. The device 800 includes a flexible membrane 808 with awindow layer 810 transparent or substantially transparent over theinfrared spectral region of interest. The window 810 protects the sensor802 from direct contact with a vessel and protects the sensor 802 fromany constraints or debris within the same. Example materials that may beused for the membrane 808 and the transparent layer 810 includeacrylics, polycarbonates, polyurethanes, nylons, cyclic olefin polymers,polyesters, high refractive index polymers. Such materials may also beused for forming a thin outer casing or housing for the other examplesdescribed herein. The materials used for the sensor 802 may be thosediscussed herein.

FIG. 9 illustrates an example application in accordance with the abovedescriptions, and in particular showing an endoscopic infrared sensordevice 900 positioned within an esophagus 902 at a location near wherethe esophagus 902 is adjacent another body cavity, in this instance theleft atrium 904. As discussed above, the two cavities 902 and 904 willabut over some region, for example, over a length of up to 5-6 cm and awidth of up to 4-5 cm depending on patient physiology. The sensor device900 has an infrared sensor probe 905 that is positioned to measureinfrared radiation corresponding to the thermal temperature of a regionof interest 906 extending around an inner wall of the esophagus 902.More specifically, the probe 905 is positioned to measure infraredradiation over a region the coincides with a region of interest 908 inthe left atrium 904 over which an energy treatment is being applied, forexample, as part of an atria arrhythmia treatment procedure.

An energy application catheter 910 (or subsystem) is positioned in theleft atrium 904 and may apply radiation such as visible, UV, IF,coherent laser energy or non-coherent emissions, RF energy, microwaveenergy, ultrasonic energy, chemical treatment, resistive heating, orother energy types to the region of interest 908. In the illustratedexample the catheter 910 is an ablation catheter applying RF ablationenergy 912 to the region of interest 908, for example, for treatment ofarrhythmia. The ablation catheter 910 may be about 4 mm in diameter.Although the details are not shown, the catheter 910 may be anirrigated, cooled catheter with sufficient shielding to concentrateapplication of the ablation energy without providing damage ordiscomfort over regions of the catheter's length proximal to theablation end tip.

The ablation catheter 910 is to be inserted into the left atrium usingstandard techniques. Generally speaking, patients are given a localanesthetic and are sedated through intravenous medication (or mayreceive general anesthesia). The catheter 910 is inserted into thefemoral vein in the groin and tracked using x-ray guidance from thegroin into the heart. The catheter 910 is then advanced into the leftatrium 904 through a transeptal puncture (as has been widely publishedpreviously or through a patent foramen ovale. Those of ordinary skill inthe art will appreciate that other insertion techniques may be employed.In contrast to the catheter 910, the probe 905 is generally administeredorally through the mouth and into the esophagus 902, and can be apassive catheter or a steering catheter device. While endocardialablation techniques are described hereinabove, it will be appreciatedthat endocardial ablation techniques may be used instead and similarlyintegrated into a feedback control configuration with the sensor probesassemblies described herein.

The probe 910 is connected to a control apparatus 914 that includes aprocessor 916 for controlling, among other things, the power output ofthe probe 910. The apparatus 914 may thus be a processor controlledmachine executing instructions to control operation of the probe 910.The apparatus 914 may optionally include a display 918 for providingvisual indications to a user, such as operating power levels,temperature readings, and/or images of the left atrium 904 if anendoscopic imaging probe is used. The apparatus 914 further includes aninput device 920, such as a keyboard, GUI interface touch screen, touchpad, handheld device, etc. that allows a user to input power settinglevels, temperature thresholds, patient data, etc. The input device 920may be integrated with the display 918.

To prevent left atrial ablation from inducing necrosis or damage to theesophageal wall leading to fistula formation, the probe 905—any of theinfrared sensor probes described herein may be used —senses the thermalconditions in the esophagus 902 resulting from the ablation treatment inthe left atrium 904. In an example, infrared radiation is collected bythe probe 905 and fed to a sensor 922 connected to the processor 916which may execute instructions to determine temperature measurementsfrom the esophagus 902. For example, the processor 916 may determine amaximum measured temperature in the esophagus 902, in response to whichthe processor 916 may compare that maximum temperature to a baselinecalibration temperature or a threshold temperature to determine theamount of temperature change in the esophagus 902 and/or whether thetemperature at a location in the esophagus 902 has increased beyond athreshold amount. The temperature threshold value may be provided by auser through the input device 920, for example. If the processor 916determines that the sensed temperature is above a temperature thresholdindicating potential damage to the esophageal wall, then the processor916 may indicate a warning signal on the display 918 to identify theundesired temperature range to the user. The processor 916 may thencommunicate with an ablation device controller 924 to provide datainstructing that controller to reduce the ablative RF energy 912 appliedto the left atrium 904. The controller 924 is part of a dedicatedablation delivery assembly in the illustrated application and isinterfaced with the probe controller 914 through data communicationinterfaces (or ports) 926 and 928. The processor 916 may be designed toprovide a turn-off instruction to the controller 924, such that inresponse the controller 924 turns off the ablation energy source 924altogether. This turn-off condition, whether controlled by deference tocontroller 914 as the master controller or by the controller 924directly, is useful when the temperature increase is such that necrosisor esophageal damage appears imminent. In some such examples, thecontrol apparatus 914 may apply different threshold levels such that ata low temperature threshold only a warning indication is provided to theuser (e.g., color coding a temperature value or temperature indicationinsignia); but when the temperature value increases past a highthreshold level, the control apparatus 914 sends a turn-off signal tothe controller 924.

In some examples the probe 910 may have its own feedback control using atemperature sensor within the left atrium 904. In such instances, theprocessor 916 would control probe operation based on multipletemperature sensors, one of the vessel being affected (e.g., the leftatrium 904) and the other for an adjacent vessel (e.g., the esophagus902) containing the infrared sensor. In any event, in these examples theinfrared sensor may be used to automatically control the amount oftreatment energy applied during a procedure in an adjacent body cavity.

In other examples, both the infrared sensor probe and the ablation probemay be used in the same bodily cavity to as part of a feedback control.

The device 900 is also shown with an alternative apparatus forpreventing heat damage to the esophagus 902. The sensor probe 905 isshown with an optional application catheter 930 (cooling subsystem) orlumen that is connected to an applicant source 932 and controlled byapparatus 914 to release the applicant to the region of interest 906,upon detection of a high temperature condition. For example, thecatheter 930 may have an opening at a distal end at the point of thewide angle lens of the sensor probe 905 and which releases cool water,liquid nitrogen, or another cooled fluid designed to reduce thetemperature in the esophagus 902 upon contact. Preferably, the openingwould be configured to create a spray effect where the cooling fluid iscontacted over the entire region of interest 906, as the particularlocation of the excessive temperature over the region of interest maynot be known. In other examples, the opening may extend around only aportion of the circumference of the probe 905, i.e., less than 360°, butwhere the opening is facing the heart side of the esophagus 902.Preferably, the opening is designed to result in the fluid being appliedalong the longitudinal axis of the esophagus 902 as well. The amount ofapplicant fluid used is controlled by the control apparatus 914, and maybe delivered as a continuous application or through intermittent, pulsedapplications of fluids. In some examples, the applicant fluid may bedelivered in one or more puffs sufficient enough to cool the hightemperature region.

The catheter 930 may be a dedicated device fused to, bonded to,otherwise attached to, the sensor probe catheter 905. In other examples,the catheter 930 may be implemented as an outer lumen shell surroundingthe probe 905 from a proximal end at the control apparatus 914 to adistal end that is near but short of the distal-most end over whichinfrared detection occurs. The catheter 930 may be controlled by thecontrol apparatus 914 or separately from the control of the probe 905.

In cryoablation applications, the catheter 930 may be a heatingsubsystem designed to apply a heating fluid to the esophagus 902 toavoid thermal damage.

Preferably, the sensing probes described herein are disposable devices,either single use or limited use assemblies to better ensure biologicalinertness and medical safety. The entire catheter device may bedisposable, or each probe sensor may have an outer sheath that isdisposable after a single use. The sheath would be formed of an infraredtransparent material, but one that can be easily removed from theunderlying sensor probe. In some examples, the sensing probes can berestricted use devices that must be registered with a control apparatus914 prior to operation. The control apparatus 914 therefore mayselectively enable or disable probes from operation based on whetherthere has been a proper registration of a probe. Such registration maybe achieved through sensor probes with embedded identification chips atthe connector end where the probe engages the control apparatus, throughbar code scanning, or other known registration techniques. Suchtechniques are useful in that they can limit the amount of time betweenwhich a sensor probe has been registered and when the sensor probe isused in a medical procedure, and do so separately from their ability tolimit the number of times a sensor probe can be used.

Alternatively to ablation, the catheter 910 may be a cryoablation deviceused to destroy cardiac tissue and thereby eliminate arrhythmogenicfoci. In such an example, the probe 905 would be configured to monitorfor excessive decreases in temperature in the esophagus 902 andresulting from cryoablation application in the left atrium 904. In fact,an advantage of the some implementations of the present techniques isthat a single infrared probe device may be used for ablation orcryoablation applications by using a controller that identifies bothexcessively high and excessively low temperatures based on the IF valuessensed by the probe sensor array.

While the examples described herein are described in the context of aninfrared sensor device, the sensors may be used for non-thermaldetection applications such that non-infrared radiation may be detectedinstead. The optic fiber channels may collect light across a range offrequencies, i.e., UV, visible, near-infrared, far-infrared, and whichmay be used by a processor to determine physical characteristics withina body cavity. In some examples, sensor probes as described herein maybe combined with light sources that illuminate a portion of a bodycavity, where reflected light or fluorescence, etc. may then be sensedby an optic fiber channel assembly capable of measuring across a volumeof interest to determine characteristics of the cavity. For example,during a chemical treatment, a light source may be used to illuminate atreatment region of interest, and a sensor may measure for radiationover a characteristic spectral region, or regions, corresponding to thattreatment chemical to determine if it is present in the region ofinterest.

In these or any other examples described herein an optical filterelement may be used to selectively pass only a region of wavelengths tothe infrared (or other) sensor apparatus. This may improvesignal-to-noise ratios in the sensor apparatus, as well as reduceaffects such as blooming or flashes than can occur with infraredsensors. Of course, these and other techniques for optimizingmeasurement of the collected radiation will be known and thus are notfurther described herein.

Various modifications and implementations will be apparent to persons ofordinary skill in the art based on the foregoing. For example, whilefiber-optic channels are illustrated as having a single window, orwide-angle lens, for collecting infrared radiation, it will beappreciated that each channel may have multiple windows for radiationcollection. Furthermore, while multiple channels are illustrated in someexamples, it will be appreciated that fewer channels may be used, and infact that one or more channels may be sufficient, where those one ormore channels may each have one or more infrared radiation windows.

At least some of the various blocks, operations, and techniquesdescribed above may be implemented in hardware, firmware, software, orany combination of hardware, firmware, and/or software. When implementedin software or firmware, the software or firmware may be stored in anycomputer readable memory such as on a magnetic disk, an optical disk, orother storage medium, in a RAM or ROM or flash memory, processor, harddisk drive, optical disk drive, tape drive, etc. Likewise, the softwareor firmware may be delivered to a user or a system via any known ordesired delivery method including, for example, on a computer readabledisk or other transportable computer storage mechanism or viacommunication media. Communication media typically embodies computerreadable instructions, data structures, program modules or other data ina modulated data signal such as a carrier wave or other transportmechanism. The term “modulated data signal” means a signal that has oneor more of its characteristics set or changed in such a manner as toencode information in the signal. By way of example, and not limitation,communication media includes wired media such as a wired network ordirect-wired connection, and wireless media such as acoustic, radiofrequency, infrared and other wireless media. Thus, the software orfirmware may be delivered to a user or a system via a communicationchannel such as a telephone line, a DSL line, a cable television line, afiber-optics line, a wireless communication channel, the Internet, etc.(which are viewed as being the same as or interchangeable with providingsuch software via a transportable storage medium). The software orfirmware may include machine readable instructions that are capable ofcausing one or more processors to perform various acts.

Although the present invention has been described in severalembodiments, a myriad of changes, variations, alterations,transformations, and modifications may be suggested to one skilled inthe art, and it is intended that the present invention encompass suchchanges, variations, alterations, transformations, and modifications asfalling within the spirit and scope of the appended claims.

What is claimed:
 1. An endoscopic system for measuring infraredradiation in a vessel, the endoscopic system comprising: an endoscopicdevice comprising a housing membrane having a distal end and atransparent outer layer around a periphery of the housing membrane andextending longitudinally from the distal end to define a side volume ofinterest, and an optical infrared sensor array comprising a plurality ofinfrared sensors extending longitudinally along and circumferentiallyabout a longitudinal axis of the endoscopic device to detect infraredradiation over the side volume of interest; and a control apparatuscomprising a processor, and a computer-readable medium havingcomputer-executable instructions that, when executed, cause theprocessor to, a) determine temperature data for the side volume ofinterest in response to infrared data from the infrared sensor array, b)determine if the temperature data is in a temperature region of concernin the vessel, and c) provide a temperature control signal to asubsystem to instruct the subsystem to reduce temperature in the vessel.2. The endoscopic system of claim 1, wherein the infrared sensor arrayis disposed to detect the infrared radiation over a 360° volume in realtime.
 3. The endoscopic system of claim 1, wherein the temperatureregion of concern is when the temperature data for the side volume ofinterest is above a high temperature threshold.
 4. The endoscopic systemof claim 1, wherein the temperature region of concern is when thetemperature data for the side volume of interest is below a lowtemperature threshold.
 5. The endoscopic system of claim 1, wherein thesubsystem is an ablation catheter in an adjacent vessel.
 6. Theendoscopic system is of claim 1, wherein the subsystem is an applicantcatheter connected to a fluid source having a cooling fluid that whenapplied to the vessel reduces the temperature in the vessel.